Journal of Plant Research

, Volume 119, Issue 3, pp 205–215

Diversity of secondary endosymbiont-derived actin-coding genes in cryptomonads and their evolutionary implications

  • Goro Tanifuji
  • Mayumi Erata
  • Ken-ichiro Ishida
  • Naoko Onodera
  • Yoshiaki Hara
Regular Paper

DOI: 10.1007/s10265-006-0263-5

Cite this article as:
Tanifuji, G., Erata, M., Ishida, K. et al. J Plant Res (2006) 119: 205. doi:10.1007/s10265-006-0263-5

Abstract

In the secondary endosymbiotic organisms of cryptomonads, the symbiont actin genes have been found together with the host one. To examine whether they are commonly conserved and where they are encoded, host and symbiont actin genes from Pyrenomonas helgolandii were isolated, and their specific and homologous regions were digoxigenin (DIG) labeled separately. Using these probes, Southern hybridization was performed on 13 species of cryptomonads. They were divided into three groups: (1) both host and symbiont actin gene signals were detected, (2) only the host actin gene signal was detected, and (3) host and unknown actin signals were detected. The phylogenetic analysis of these actin gene sequences indicated that the evolutionary rates of the symbiont actin genes were accelerated more than those of the hosts. The unknown actin signals were recognized as the highly diverged symbiont actin genes. One of the diverged symbiont actin sequences from Guillardia theta is presumed to be as a pseudogene or to its precursor. Southern hybridizations based on the samples divided by pulsed-field gel electrophoresis showed that all actin genes were encoded by the host nuclei. These results possibly represent the evolutionary fate of the symbiont actin gene in cryptomonads, which was firstly transferred from the symbiont nucleus or nucleomorph, to the host nucleus and became a pseudogene and then finally disappeared there.

Keywords

Cryptomonads Nucleomorph Symbiotic gene reorganization Symbiont actin gene 

Copyright information

© The Botanical Society of Japan and Springer-Verlag 2006

Authors and Affiliations

  • Goro Tanifuji
    • 1
  • Mayumi Erata
    • 2
  • Ken-ichiro Ishida
    • 3
  • Naoko Onodera
    • 1
  • Yoshiaki Hara
    • 4
  1. 1.Graduate School of Engineering and ScienceYamagata UniversityYamagata 990-8560Japan
  2. 2.Global Environmental ForumIbarakiJapan
  3. 3.Division of Life Sciences, Graduate School of Natural Science and TechnologyKanazawa UniversityKanazawaJapan
  4. 4.Department of Biology, Faculty of ScienceYamagata UniversityYamagataJapan

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